Refrigeration apparatus



L. B. M. BUCHANAN REFRIGERATION APPARQTUS Filed Nov. 9, 1939 FAQ. i.

N WM v M w m March 5, 1940.

WITNESSESZ Patented Mar. 5, 1940 UNITED STATES PATENT OFFICE REFRIGERATION APPARATUS Application November 9, 1939, Serial No. 303,521

8 Claims.

5 1937. The invention relates to refrigerating apparatus and has for an object to provide improved apparatus of this kind.

A further object of the invention is to limit the maximum temperature of the media cooled by a refrigerating element and the minimum temperature of the element.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a diagrammatic view of refrigerating apparatus constructed and controlled in accordance with my invention; and

Fig. 2 is an enlarged view, partly in section, of a portion of the evaporator shown in Fig: 1.

Reference will now be had to the drawing wherein I have shown my invention applied to a conventional, single evaporator refrigerator of the domestic type including a cabinet structure 4| that defines a zone or chamber 42 for the storage of perishables and which is maintained at a relatively high refrigerating temperature. Cooling of the air in the zone 42 is effected by a suitable evaporator structure 43 that encloses a relatively low temperature-zone 43a. Trays 44 for fluid to be congealed or for containing prod- ,ucts to be cooled to a relatively low temperature are disposed in a low temperature zone 43a.

Circulation of refrigerant through the evapo- 40 I1 and .a condenser |8for liquefying the gaseous refrigerant. Cooling of the condenser is effected in any well known manner, such as, for example, by means of a fan IS. The refrigerant vaporized in the evaporator 43 is conveyed to the compressor l6 by a suction conduit 45 and the compressed refrigerant is delivered to the condenser 18 through a conduit 25. Liquefied refrigerant is conveyed from the condenser ill to the evaporator 43 through a conduit 46 having an expansion device such as, for example, a capillary tube 41 connected therein. In accordance with my invention, the evaporator 43 includes a portion 48 shown by way of example as a conduit that extends into the air in the zone 42 and which defines a container for refrigerant during operation of the condensing unit l5. Shortly after the condensing unit 15 is rendered inactive, the conduit 48 contains only refrigerant gas, the conduit 48 being above the normal level of re frigerant in the evaporator 43, as shown in'Fig. 2 at 58. The supply conduit 46 is shown connected to the conduit 48 so that the refrigerant supplied to the evaporator 43 passes through the conduit 48, but the refrigerant may be supplied to the evaporator in any suitable manner.

Operation of the condensing unit l5 is automatically controlled in accordance with thejtemperature of the evaporator portion .or conduit 48 so that circulation of refrigerant is initiated in response to a predetermined high temperature of the conduit 48 and is terminated in response to .a predetermined low temperature thereof.

The thermostatic control which is generally indicated at 26 may be of the conventional gas type and includes a bellows 29 connected by a tube 3| to a bulb 21, the latter being disposed in'heat transfer relation with the evaporator portion 48. The bellows actuates a lever 32 and is biased by a spring 33 that maybe adjusted in any suitable manner, such as, for example, by an adjusting screw 34 disposed in a location convenient to the operator. A movable switch member 35 is connected to the lever 32 by a snap-acting, overcenter spring 36 and is engageable with a stationary adjustable contact 31. The contacts 35 and 31 are connected in an electrical circuit 88 for controlling energization of the motor H. The adjusting screw 34 determines the temperatures at which the motor I! is started and stopped. By adjusting the contact 31 the temperature difier ential orthe differences between the temperatures at which the motor I! is started and stopped may be varied.

The mass of the conduit 48 is small compared to the mass of the main body of the evaporator 43 so that during inactive periods of the compressor, the temperature of the conduit 48 increases more rapidly than the temperature of the evaporator 43 due to heat load in the zone 42 and because only gas is present in the conduit 48 a short time after the condensing unit I5 is rendered inactive. Conversely, the temperature of the conduit 48 is reduced more rapidly than the temperature of the evaporator 43 during operating periods of the compressor, both the evaporator .43 and. the conduit 48 substantially assuming the .same temperature after the compressor has operated a short time.

It will be apparent, therefore, that the temperature of the conduit portion 48 is primarily a function of the temperature of the air in the zone 42 at the time that the compressor I6 is started and a function of refrigerant temperature at the time the compressor is stopped. Because of the rapid reduction in temperature of the conduit 48 during operating periods of the compressor, the temperature of the low temperature refrigerant is quickly reflected by the thermal responsive bulb 21,

Operation During operation of the compressor [6, the temperatures of the evaporator 43 and its conduit portion 48 are progressively depressed to a predetermined low value, for example, 20 F., at which time the thermostat 26 operates to stop the compressor. The cold evaporator abstracts heat from the air in the chambers 42 and 43a, the former being at a temperature of approximately 40 F. when the compressor is stopped and the latter being cooled to a lower temperature, for example, 25 F.

During inactive periods of the compressor 16, the temperature of the evaporator 43 and its conduit portion 48 rise due to the heat load thereon. The temperature of the conduit portion 48 increases faster than the temperature of the body of the evaporator 43 due toits small mass and because it is substantially devoid of liquid refrigerant and is subjected only to the relatively high temperature air in the zone 42, while the evaporator 43, on the other hand, defines a relatively large mass at a low temperature and is, furthermore, subjected to the low temperature products, such as ice cubes, that are stored in the zone 43a. Accordingly, the conduit portion 48 increases in temperature rapidly and attains, substantially, the temperature of the air in the chamber 42. Operation of the compressor is initiated when the temperature of the bulb 21 increases to a predetermined degree, for example, 44 F. At this time, however, the temperature of the evaporator 43 is at a lower value of, for example, 34 F. Accordingly, the evaporator operates between temperatures of 25 F. and 34 F. and the conduit portion 48 thereof between temperatures of 25 F. and 44 F. It will be apparent from the foregoing that the compressor I5 is started primarily in response to a predetermined temperature of the air in the zone 42 and is stopped primarily in response to a predetermined low temperature in the evaporator 43.

The apparatus described heretofore represents an improvement over prior systems wherein the compressor is controlled only by air temperature or evaporator temperature. An increase in the ambient or room temperature increases the heat leakage into the zone 42 and tends to increase the air temperature. This increase is quickly reflected by my improved apparatus so that the maximumair temperature in the zone 42 may be maintained at a desired value regardless of changes in ambient temperature. Furthermore, relatively fast freezing of liquids in the trays is obtained, as operation of the compressor is terminated by the temperature of the evaporator 42 and its portion 48. In prior systems where evaporator temperature only controls operation of the compressor, the air temperature in the refrigerated zone fluctuates with ambient temperature changes and where air temperature is the clontrolling factor, freezing of liquids is relatively s ow.

It will be apparent from the foregoing that I have provided improved refrigerating apparatus wherein a single control may be employed for maintaining the temperature of the air in the cabinet of the single evaporator machine below a predetermined value irrespective of ambient or room temperatures while providing for rapid freezing of liquids by the evaporator.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims. 7

What I claim is:

1. In a refrigerating apparatus, the combination of an evaporator, means for condensing refrigerant vaporized in the evaporator, pressure reducing means for conveying condensed refrigerant from the condensing means to the evaporator, said evaporator including a conduit portion of small mass compared with the mass of the evaporator, which conduit portion contains only refrigerant gas a short time after the condensing means is rendered inactive and rises in temperature faster than the evaporator at that time. said conduit portion containing refrigerant liquid and substantially assuming the temperature of the evaporator during operation of the condensing means and a thermostatic controller for controlling operation of the condensing means and including a heat-responsive element disposed in heat transfer relation with said conduit portion.

2. In refrigerating apparatus, the combination of an evaporator for refrigerating zone, means for condensing refrigerant vaporized in the evaporator, pressure reducing means for conveying condensed refrigerant from the condensing means to the evaporator, said evaporator including a conduit portion of small mass compared with the mass of the evaporator, which conduit portion extends into said zone and contains only refrigerant gas a short time after the condensing means is rendered inactive and rises in temperature faster than the evaporator at that time, said conduit portion containing refrigerant liquid and substantially assuming the temperature of the evaporator during operation of the condensing means and a thermostatic controller for controlling operation of the condensing means and including a heat-responsive element disposed in heat transfer relation with said conduit portion.

3. In refrigerating apparatus, the combination of an evaporator containing a body of refrigerant liquid therein, means for condensing refrigerant vaporized in the evaporator, pressure reducing means for conveying condensed refrigerant from the condensing means to the evaporator, said evaporator including a conduit portion of small mass compared with the mass of the evaporator and having its, inlet disposed above the level of the refrigerant in the evaporator, which conduit portion contains only refrigerant gas a short time after the condensation means is rendered inactive and rises in temperature faster than the evaporator at that time, said conduit portion containing refrigerant liquid and substantially assuming the temperature of the evaporator during operation of the condensing means and a thermostatic controller for controlling operation' of the condensing means and including a heat- Far responsive element disposed in heat transfer relation with said conduit portion.

4. In refrigerating apparatus, the combination of an evaporator, means for condensing at relatively high pressure the refrigerant vaporized in the evaporator at relatively low pressure, means for reducing the pressure of the condensed refrigerant, said evaporator including a conduit member of relatively low heat storage capacity compared with the heat storage capacity of the evaporator for delivering the low pressure condensed refrigerant to the evaporator, said conduit member having a portion thereof spaced from the evaporator in a region whose temperature is higher than the evaporator temperature, said conduit portion containing only refrigerant gas a short time after the condensing means is rendered inactive, and containing refrigerant liquid during active periods of the condensing means, and a thermostatic controller for controlling operation of the condensing means and including a\ heat-responsive element in heat transfer relation with said portion of the conduit member.

5. In refrigerating apparatus, the combination of an evaporator, means for condensing at relatively high pressure the refrigerant vaporized in the evaporator at relatively low pressure, an expansion device having an elongated passage of fixed flow area for conveying condensed refrigerant from the condensing means to the evaporator and for effecting a reduction in the pressure thereof, said expansion device including a con- (iuit portion of relatively low heat storage capacity for delivering low pressure condensed refrigerant from the expansion device to the evaporator and a thermostatic controller having a heat responsive element disposed in heat transfer relation with said conduit portion, said controller initiating and terminating operation of the condensing means in response to predetermined high and low temperatures of the conduit portion, respectively, said heat-responsive element being disposed in spaced relation with the evaporator.

6. In refrigerating apparatus, the combination of an evaporator, means for condensing at relatively high pressure the refrigerant vaporized in the evaporator at relatively low pressure, an expansion device for conveying the condensed refrigerant from the condenser to the evaporator and for effecting a reduction in the pressure thereof, said evaporator including a main portion and a refrigerant conveying portion for receiving the low pressure condensed refrigerant discharged from said expansion device, said refrigerant conveying portion of the evaporator being of relatively small mass when compared with the mass of the main portion of the evap0 rator and a thermostatic controller for controlling the operation of the refrigerant condensing means and including a heat-responsive element spaced from the main portion of the evaporator and discharged in heat transfer relation with said refrigerant conveying portion, said thermostatic controller initiating and terminating operation of the refrigerant condensing means in response,

- respectively, to predetermined high and low temperatures of the refrigerant conveying portion of the evaporator, the arrangement, being such that, during operation of the refrigerant condensing means, said refrigerant conveying portion contains liquid refrigerant and is depressed in temperature to a value substantially equal to the temperature of the refrigerant vaporized in the evaporator and, shortly after the refrigerant condensing means is rendered inactive, said refrigerant conveying portion contains only refrigerant gas and is increased in temperature to a value higher than the temperature of the refrigerant within the main portion' of the evaporator.

7. In refrigerating apparatus, the combination ofan evaporator having a body of liquid therein, means for condensing at relatively high pressure the refrigerant vaporized in the evaporator at relatively low pressure, an expansion device for conveying the condensed refrigerant from the condenser to the evaporator and for effecting a reduction in the pressure thereof, said evaporator including a main portion and a refrigerant conveying portion having its inlet disposed above the level of the refrigerant in said evaporator and receiving the low pressure condensed refrigerant discharged from said expansion device, said refrigerant conveying portion of the evaporator a .that, during operation of the refrigerant condensing means, said refrigerant conveying portion contains liquid refrigerant and is depressed in temperature to a. value substantially equal to the temperature of the refrigerant vaporized in the evaporator and, shortly after the refrigerant condensing means is rendered inactive, said refrigerant conveying portion contains only refrigerant gas and is increased in temperature to a value higher than the temperature of the refrigerant within the main portion of the evaporator.

8. In refrigerating apparatus, the combination of means defining a zone to be refrigerated, an evaporator embodying a main portion and a refrigerant conveying portion for abstracting heat from the media in said zone, means for condensing at relatively high pressure the refrigerant vaporized in the evaporator at relatively low pressure, an expansion device for conveying condensed refrigerant from the condenser to the refrigerant conveying portion of the evaporator and for eflecting a reduction in the pressure thereof, said refrigerant conveying portion of the evaporator extending into the media of said zone and being of relatively small mass when compared with the mass of the evaporator, a thermostatic controller for controlling the operation of the refrigerant condensing means and including a heat-responsive element disposed in heat transfer relation with said refrigerant conveying portion of the evaporator and in spaced relation with respect to the main portion of the evaporator, said thermostatic controller initiating and terminating operation of the refrigerant condensing means in response, respectively, to predetermined high and low temperatures of the refrigerant conveying portion of the evaporator, the arrangement being such that, during operation of the refrigerant condensing means the refrigerant conveying portion of the evaporator contains liquid and is depressed in temperature to a value substantially equal to the temperature of the refrigerant vaporized in the main 'portion of the evaporator and, during inactive periods of the refrigerant condensing means, the refrigerant conveying portion contains only refrigerant gas and is increased in temperature to a value that is higher than the temperature of the refrigerant within the main portion of the evaporator and which is affected materially by the temperature of the media being refrigerated.

LESLIE B. M. BUCHANAN.

CERTIFICATE OF CORRECTION- Patent No. 2,192,818.

ofthe above numbered patent requiring correction as follows: Page 2, second column, line 18, claim 1, strike out the article "a"; line 58, claim 2, before "zone" insert a; line 68, claim 5, for the word "condensation" read condensing; and that the said Letters Patent should be read with this Henry Van Arsdale, Acting Commissioner of Patents. 

